Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS64 KEWX 250020
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
720 PM CDT SUN MAY 24 2015

.AVIATION.../00Z TAFS/
CIGS HAVE LIFTED TO VFR AS DRY AIR BRIEFLY MOVES IN FROM THE
WEST...BUT MOIST S-SE FLOW WILL CAUSE CIGS TO LOWER TO MVFR AND
IFR BY 6-7Z AT SAT/SSF/AUS AND BORDERLINE MVFR-IFR BY 10Z AT DRT.
ANOTHER UPPER LEVEL DISTURBANCE WILL HELP TRIGGER ISO TSRA AT DRT
BETWEEN 12-15Z...BEFORE BECOMING MORE WIDESPREAD AT SAT/SSF/AUS
LATE MONDAY MORNING THROUGH THE AFTERNOON. A FEW HI-RES MODELS ARE
A BIT FASTER THAN THE GLOBAL MODELS AND SUGGEST SCT SHRA AND TSRA
MAY OCCUR LATE TOMORROW MORNING AHEAD OF MORE WIDESPREAD SHRA AND
TSRA TOMORROW AFTERNOON...SO HAVE ADDED IN TEMPO GROUPS BEGINNING
AT 15-16Z AT SAT/SSF/AUS AND MOVED TIMING UP AN HOUR TO ACCOUNT
FOR THIS. OTHERWISE...PREVAILING TSRA SHOULD OCCUR FOR AT LEAST A
FEW HOURS MONDAY AFTERNOON BEFORE ENDING BY EARLY MONDAY EVENING.

&&

.PREV DISCUSSION... /ISSUED 322 PM CDT SUN MAY 24 2015/

SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)...
THE SHORT BREAK FROM PRECIPITATION CONTINUES LATE THIS AFTERNOON
INTO THE OVERNIGHT HOURS. A FEW SHOWERS AND AN ISOLATED
THUNDERSTORMS ARE STILL POSSIBLE LATER THIS AFTERNOON. HAVE SEEN A
FEW ISOLATED SHOWERS BEGINNING TO FORM UP IN WILLIAMSON COUNTY.
THIS SUPPORTS WHAT THE HRRR SHOWS THROUGH THE EVENING HOURS.

DRY AIR HAS FILTERED IN BEHIND THE TWO LINES OF CONVECTION THIS
MORNING. ALL OF THE MODELS HAVE SOUTH CENTRAL TEXAS REMAINING DRY
OVERNIGHT WITH ONLY THE NAM SHOWING ANY CONVECTION/QPF OVERNIGHT.
WILL DISCOUNT THE NAM FOR NOW.

THE NEXT UPPER LEVEL DISTURBANCE IS NOW ALONG THE
CALIFORNIA/ARIZONA BORDER. THIS WILL APPROACH THE AREA MONDAY.
MODELS ARE A BIT SPLIT ON TIMING OF THE SHOWERS AND THUNDERSTORMS
TOMORROW...BUT THEY ARE IN FAIRLY GOOD AGREEMENT ON QPF AMOUNTS.
THE NAM...GFS...AND ECMWF ALL CONCENTRATE QPF ACROSS THE NORTHERN
I-35 CORRIDOR AND POINTS EAST WITH LESSER AMOUNTS ACROSS THE HILL
COUNTRY AND BEXAR COUNTY AREA. STILL THOUGH MODELS ARE SHOWING 1
TO 3 INCHES ACROSS AREAS THAT NOT ONLY HAD 1 TO 3...OR IN SOME
CASES A LOT MORE...INCHES OF A RAIN LAST NIGHT BUT HAVE ALSO HAD
SEVERAL HEAVY RAIN EVENTS OVER THE LAST FEW WEEKS...LIKE THE
BASTROP AND LEE COUNTY AREAS. THE HEAVIER STORMS TOMORROW COULD
PRODUCE LOCALLY HEAVY RAINFALL UP TO 5 INCHES. THIS SHOULD BE
ENOUGH TO CAUSE MORE FLOODING CONCERNS SO FOR THAT REASON WE WILL
BE ISSUING A FLASH FLOOD WATCH FROM 10 AM MONDAY THROUGH 1 AM ON
TUESDAY. AGAIN ALTHOUGH QPF AMOUNTS ARE EXPECTED TO BE LOWER
TOMORROW THAN THEY WERE LAST NIGHT THE ALREADY SATURATED GROUND
CANNOT TAKE ANYMORE RAINFALL LEADING TO THE ENHANCED FLASH FLOOD
RISK. THE LINE OF STORMS WILL BE FAST MOVING SO PRECIPITATION
SHOULD BE ENDING BY LATE MONDAY NIGHT.

MOST OF THE MESOSCALE MODELS BEGIN CONVECTION ACROSS THE EDWARDS
PLATEAU AS EARLY AS 7 TO 10 AM TOMORROW. EARLY ON STORMS SHOULD BE
MORE CELLULAR. EVENTUALLY THESE STORMS WILL FORM INTO A LINE OF
SHOWERS AND THUNDERSTORMS MUCH LIKE WHAT WE SAW COME THROUGH LAST
NIGHT. THIS LINE WOULD APPROACH THE I-35 CORRIDOR MID TO LATE
AFTERNOON TOMORROW. SEVERE WEATHER PARAMETERS ARE AGAIN IMPRESSIVE
FOR TOMORROW WITH FORECAST SOUNDINGS SHOWING PLENTY OF INSTABILITY
AND SHEAR TO SUPPORT NOT ONLY THE THREAT FOR LARGE HAIL AND
DAMAGING WINDS...BUT ALSO A FEW ISOLATED TORNADOES. SIMILAR TO
YESTERDAY AFTERNOON AND OVERNIGHT THE STORM MODE THAT THE STORMS
TAKE WILL MOST LIKELY DETERMINE THE MAIN THREATS. THE LONGER THE
STORMS STAY CELLULAR THE BETTER THE CHANCES FOR TORNADOES. WITH
MOST MODELS SHOWING A LINEAR SYSTEM COMING ACROSS THE I-35
CORRIDOR THE MAIN THREATS WILL BE STRAIGHTLINE WINDS...SOME
ISOLATED HAIL...AND THE POSSIBILITY OF A QLCS TORNADO OR TWO. WE
SAW SEVERAL CIRCULATIONS OR SPIN UPS ALONG THE LINE OF
THUNDERSTORMS LAST NIGHT AS IT PROGRESSED ACROSS THE AREA. A STORM
SURVEY TEAM IS CURRENT EN ROUTE TO GO DETERMINE IF THERE WERE ANY
TORNADOES OR IF THE DAMAGE WAS CAUSED BY STAIGHTLINE WINDS. MODELS
HAVE THE LINE OF STORMS THROUGH THE AREA BY 10 PM TO MIDNIGHT
MONDAY INTO EARLY TUESDAY MORNING.

IN SUMMARY...QUIET NIGHT TONIGHT...CONVECTION STARTING EARLY
TOMORROW...FLASH FLOOD WATCH STARTING AT 10 AM...CONVECTION
APPROACHING THE I-35 CORRIDOR MID TO LATE AFTERNOON WITH A THREAT
FOR LOCALLY HEAVY RAIN AND SEVERE WEATHER...MOVING OUT OF THE
AREA LATE MONDAY NIGHT INTO TUESDAY.

LONG TERM (TUESDAY THROUGH SUNDAY)...
MID WEEK SHOULD SEE A LULL IN PRECIPITATION FOR TUESDAY THROUGH
THURSDAY MORNING AS THE UPPER LEVEL PATTERN BECOMES MORE ZONAL AND
EVEN SOME WEAK RIDGING TAKES PLACE ACROSS SOUTH TEXAS. WHILE THE
PATTERN BECOMES MORE PROGRESSIVE ANOTHER TROUGH DROPS ACROSS THE
WESTERN U.S. WITH ANOTHER DISTURBANCE TRACKING ACROSS THE
SOUTHWEST U.S. BY LATE THURSDAY INTO FRIDAY. THIS WILL UP
RAIN CHANCES AGAIN INTO THE WEEKEND AS THE TROUGH ALSO DRAGS A
BOUNDARY ACROSS THE AREA. THE WET AND RAINY PATTERN LOOKS TO
CONTINUE. ANOTHER FACTOR THAT MAY PLAY INTO THE WEATHER LATE NEXT
WEEK IS THAT MODELS ARE FORMING A TROPICAL SYSTEM IN THE PACIFIC
THAT COULD SEND MOISTURE UP OUR DIRECTION.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              83  72  82  69  88 /  30  20  80  40  20
AUSTIN BERGSTROM INTL AIRPORT  82  72  82  68  87 /  30  20  80  40  20
NEW BRAUNFELS MUNI AIRPORT     84  72  83  70  87 /  20  20  80  30  20
BURNET MUNI AIRPORT            82  70  80  67  87 /  30  20  80  30  20
DEL RIO INTL AIRPORT           91  70  90  68  93 /  20  20  50  20  10
GEORGETOWN MUNI AIRPORT        81  72  80  69  87 /  30  20  80  30  20
HONDO MUNI AIRPORT             86  71  84  70  88 /  20  20  80  30  20
SAN MARCOS MUNI AIRPORT        82  73  82  70  87 /  30  20  80  40  20
LA GRANGE - FAYETTE REGIONAL   81  74  82  72  87 /  30  30  80  50  20
SAN ANTONIO INTL AIRPORT       85  73  83  72  88 /  20  20  80  30  20
STINSON MUNI AIRPORT           85  73  84  72  88 /  20  20  80  30  20

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT FOR
THE FOLLOWING COUNTIES: ATASCOSA...BANDERA...BASTROP...BEXAR...
BLANCO...BURNET...CALDWELL...COMAL...DE WITT...DIMMIT...FAYETTE...
FRIO...GILLESPIE...GONZALES...GUADALUPE...HAYS...KARNES...KENDALL...
KERR...LAVACA...LEE...LLANO...MEDINA...REAL...TRAVIS...UVALDE...
WILLIAMSON...WILSON...ZAVALA.

&&

$$

MESOSCALE/AVIATION...01
SYNOPTIC/GRIDS...09
PUBLIC SERVICE/DATA COLLECTION...30


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.